Element clef describes the characteristics of the clef. A number of different clefs is supported for the same staff, provided that they are linked to spine events. Spine identification allows to identify the position of clef changes within the score.

Attributes

event_ref, a mandatory attribute to identify the event which element clef should be linked to.

shape, which defines the shape of the clef. Main shapes in use are treble, bass, and C clefs, but percussions, tablature, and double G clefs are also supported by IEEE 1599.

staff_step, an attribute which defines the vertical position of the clef. A NIFF-like syntax has been employed: lines and spaces are numbered from the bottom line, so the value "0" represents the central-E line in a G-clef staff, "1" is the F space, "2" the G line, and so on. This mechanism is an absolute way to identify position with respect to the staff graphical symbol.

octave_num, an attribute to encode numbers over or below the clef symbol. These numbers are used when the musical line is occasionally still too high or too low to fit neatly onto the five line staff. A useful device that overcomes this problem is a commonly accepted syntax that moves the musical line up or down an octave. In music theory, to make a clef one (two) octave(s) lower a small 8va (15ma) is added beneath it; likewise, to make a clef one (two) octave(s) higher a small 8vb (15mb) is added above it. The music is read as though at a certain octave but sounds either one (two) octave(s) higher or one (two) octave(s) lower than it is written.